pH regulatory systems of marine larvae: new models for gastro-intestinal health and biomineralization in a changing environment

• Applicant: Dr. Marian Yong-An Hu
• Subject Area: Animal Physiology and Biochemistry
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403529967

Over a century the sea urchin larva has been used as a model for understanding the early development and the underlying gene regulatory network of deuterostomes. The success of the sea urchin model is because of its phylogenetic position at a critical node of the deuterostomes providing a simple system to understand processes that are very complex and difficult to study in vertebrates and humans. Despite its popularity in developmental and evolutionary biology, functional traits that dictate the evolution of developmental patterns under changing environmental conditions remain largely unknown. I will employ the highly tractable model of the sea urchin larva, that can work from the whole animal level to specific manipulations of the genetic material, to investigate pH regulatory systems relevant for gastro-intestinal-health and biomineralization of the larval skeleton. Here the sea urchin larva provides two major exciting pH regulatory systems that were recently discovered in the frame of my research: i) a highly alkaline stomach up to pH 9.5, and ii) substantial intracellular pH regulatory capacities of the calcifying primary mesenchyme cells (PMCs) that build the larval skeleton. Three main research objectives will be addressed in this project: 1) Identification of transport mechanisms responsible for alkalization of the larval sea urchin gut 2) Evaluating the role of an alkaline gut in pathogen defense 3) Identification of pH regulatory systems in primary mesenchyme cells critical for biomineralization. The results will be embedded in the context of environmental change including the fact that pH regulation is a key process for the resilience of marine organisms to anthropogenic-driven ocean acidification.To understand the role and the mechanisms of these two pH regulatory systems, molecular, protein biochemical, fluorimetric and electrophysiological techniques will be applied in this project. The experimental strategy will be a systematic and stepwise examination of the pH regulatory machinery in the gastric epithelium and PMCs including established components as well as pioneer approaches. The expected mechanistic understanding will help to perform specific manipulations to study the role of pH regulation in pathogen defense and biomineralization in the sea urchin larva.The long-term vision is to establish a set of model organisms that can work from the mechanistic description of pH regulatory systems, through their role in gastro-intestinal health and biomineralization up to predictions on the ecological and evolutionary scale.

• DFG Programme: Independent Junior Research Groups